Unlike a primary battery which is incapable of being recharged, a secondary battery (rechargeable battery) can be repeatedly charged and discharged. A low-capacity rechargeable battery is used as a power supply for small electronic devices such as cellular phones, notebook computers, and camcorders, while a medium or high-capacity rechargeable battery is used as a power supply for driving motors in hybrid vehicles and the like.
A high power rechargeable battery using a non-aqueous electrolyte of high energy density has been recently developed. A plurality of these rechargeable batteries can be coupled in series to form a large capacity battery module so that the high power rechargeable battery may be used to drive a device requiring high power (e.g., a motor in an electric vehicle).
Such a rechargeable battery is inserted into a tray for transport, and the thickness of the tray needs to be minimized for cost reduction and load reduction. However, when the thickness of the tray is minimized, strength of the tray is weakened so that the height of the tray is decreased. In addition, when the height of the tray is decreased, the number of batteries that can be received in a single tray is reduced.